vidioc-enuminput.rst

.. -*- coding: utf-8; mode: rst -*-

.. _VIDIOC_ENUMINPUT:

**********************
ioctl VIDIOC_ENUMINPUT
**********************

Name
====

VIDIOC_ENUMINPUT - Enumerate video inputs


Synopsis
========

.. cpp:function:: int ioctl( int fd, int request, struct v4l2_input *argp )


Arguments
=========

``fd``
    File descriptor returned by :ref:`open() <func-open>`.

``request``
    VIDIOC_ENUMINPUT

``argp``


Description
===========

To query the attributes of a video input applications initialize the
``index`` field of struct :ref:`v4l2_input <v4l2-input>` and call the
:ref:`VIDIOC_ENUMINPUT` ioctl with a pointer to this structure. Drivers
fill the rest of the structure or return an ``EINVAL`` error code when the
index is out of bounds. To enumerate all inputs applications shall begin
at index zero, incrementing by one until the driver returns ``EINVAL``.


.. _v4l2-input:

.. flat-table:: struct v4l2_input
    :header-rows:  0
    :stub-columns: 0
    :widths:       1 1 2


    -  .. row 1

       -  __u32

       -  ``index``

       -  Identifies the input, set by the application.

    -  .. row 2

       -  __u8

       -  ``name``\ [32]

       -  Name of the video input, a NUL-terminated ASCII string, for
	  example: "Vin (Composite 2)". This information is intended for the
	  user, preferably the connector label on the device itself.

    -  .. row 3

       -  __u32

       -  ``type``

       -  Type of the input, see :ref:`input-type`.

    -  .. row 4

       -  __u32

       -  ``audioset``

       -  Drivers can enumerate up to 32 video and audio inputs. This field
	  shows which audio inputs were selectable as audio source if this
	  was the currently selected video input. It is a bit mask. The LSB
	  corresponds to audio input 0, the MSB to input 31. Any number of
	  bits can be set, or none.

	  When the driver does not enumerate audio inputs no bits must be
	  set. Applications shall not interpret this as lack of audio
	  support. Some drivers automatically select audio sources and do
	  not enumerate them since there is no choice anyway.

	  For details on audio inputs and how to select the current input
	  see :ref:`audio`.

    -  .. row 5

       -  __u32

       -  ``tuner``

       -  Capture devices can have zero or more tuners (RF demodulators).
	  When the ``type`` is set to ``V4L2_INPUT_TYPE_TUNER`` this is an
	  RF connector and this field identifies the tuner. It corresponds
	  to struct :ref:`v4l2_tuner <v4l2-tuner>` field ``index``. For
	  details on tuners see :ref:`tuner`.

    -  .. row 6

       -  :ref:`v4l2_std_id <v4l2-std-id>`

       -  ``std``

       -  Every video input supports one or more different video standards.
	  This field is a set of all supported standards. For details on
	  video standards and how to switch see :ref:`standard`.

    -  .. row 7

       -  __u32

       -  ``status``

       -  This field provides status information about the input. See
	  :ref:`input-status` for flags. With the exception of the sensor
	  orientation bits ``status`` is only valid when this is the current
	  input.

    -  .. row 8

       -  __u32

       -  ``capabilities``

       -  This field provides capabilities for the input. See
	  :ref:`input-capabilities` for flags.

    -  .. row 9

       -  __u32

       -  ``reserved``\ [3]

       -  Reserved for future extensions. Drivers must set the array to
	  zero.



.. _input-type:

.. flat-table:: Input Types
    :header-rows:  0
    :stub-columns: 0
    :widths:       3 1 4


    -  .. row 1

       -  ``V4L2_INPUT_TYPE_TUNER``

       -  1

       -  This input uses a tuner (RF demodulator).

    -  .. row 2

       -  ``V4L2_INPUT_TYPE_CAMERA``

       -  2

       -  Analog baseband input, for example CVBS / Composite Video,
	  S-Video, RGB.



.. _input-status:

.. flat-table:: Input Status Flags
    :header-rows:  0
    :stub-columns: 0


    -  .. row 1

       -  :cspan:`2` General

    -  .. row 2

       -  ``V4L2_IN_ST_NO_POWER``

       -  0x00000001

       -  Attached device is off.

    -  .. row 3

       -  ``V4L2_IN_ST_NO_SIGNAL``

       -  0x00000002

       -

    -  .. row 4

       -  ``V4L2_IN_ST_NO_COLOR``

       -  0x00000004

       -  The hardware supports color decoding, but does not detect color
	  modulation in the signal.

    -  .. row 5

       -  :cspan:`2` Sensor Orientation

    -  .. row 6

       -  ``V4L2_IN_ST_HFLIP``

       -  0x00000010

       -  The input is connected to a device that produces a signal that is
	  flipped horizontally and does not correct this before passing the
	  signal to userspace.

    -  .. row 7

       -  ``V4L2_IN_ST_VFLIP``

       -  0x00000020

       -  The input is connected to a device that produces a signal that is
	  flipped vertically and does not correct this before passing the
	  signal to userspace. Note that a 180 degree rotation is the same
	  as HFLIP | VFLIP

    -  .. row 8

       -  :cspan:`2` Analog Video

    -  .. row 9

       -  ``V4L2_IN_ST_NO_H_LOCK``

       -  0x00000100

       -  No horizontal sync lock.

    -  .. row 10

       -  ``V4L2_IN_ST_COLOR_KILL``

       -  0x00000200

       -  A color killer circuit automatically disables color decoding when
	  it detects no color modulation. When this flag is set the color
	  killer is enabled *and* has shut off color decoding.

    -  .. row 11

       -  :cspan:`2` Digital Video

    -  .. row 12

       -  ``V4L2_IN_ST_NO_SYNC``

       -  0x00010000

       -  No synchronization lock.

    -  .. row 13

       -  ``V4L2_IN_ST_NO_EQU``

       -  0x00020000

       -  No equalizer lock.

    -  .. row 14

       -  ``V4L2_IN_ST_NO_CARRIER``

       -  0x00040000

       -  Carrier recovery failed.

    -  .. row 15

       -  :cspan:`2` VCR and Set-Top Box

    -  .. row 16

       -  ``V4L2_IN_ST_MACROVISION``

       -  0x01000000

       -  Macrovision is an analog copy prevention system mangling the video
	  signal to confuse video recorders. When this flag is set
	  Macrovision has been detected.

    -  .. row 17

       -  ``V4L2_IN_ST_NO_ACCESS``

       -  0x02000000

       -  Conditional access denied.

    -  .. row 18

       -  ``V4L2_IN_ST_VTR``

       -  0x04000000

       -  VTR time constant. [?]



.. _input-capabilities:

.. flat-table:: Input capabilities
    :header-rows:  0
    :stub-columns: 0
    :widths:       3 1 4


    -  .. row 1

       -  ``V4L2_IN_CAP_DV_TIMINGS``

       -  0x00000002

       -  This input supports setting video timings by using
	  VIDIOC_S_DV_TIMINGS.

    -  .. row 2

       -  ``V4L2_IN_CAP_STD``

       -  0x00000004

       -  This input supports setting the TV standard by using
	  VIDIOC_S_STD.

    -  .. row 3

       -  ``V4L2_IN_CAP_NATIVE_SIZE``

       -  0x00000008

       -  This input supports setting the native size using the
	  ``V4L2_SEL_TGT_NATIVE_SIZE`` selection target, see
	  :ref:`v4l2-selections-common`.


Return Value
============

On success 0 is returned, on error -1 and the ``errno`` variable is set
appropriately. The generic error codes are described at the
:ref:`Generic Error Codes <gen-errors>` chapter.

EINVAL
    The struct :ref:`v4l2_input <v4l2-input>` ``index`` is out of
    bounds.